Adaptive Control For Motor Fan With Multiple Speed Taps

ABSTRACT

A circulator blower controller for a circulator blower of a heating, ventilation, and air conditioning (HVAC) system of a building includes an interface configured to receive a demand signal with an operating mode from a thermostat. A switching circuit selectively connects power to a tap of a motor of the circulator blower. A data store configured to store a mapping from a speed to the tap. For each tap, a processor observes power consumed by the circulator blower while power is connected to the tap by the switching circuit. The processor determines the mapping by sorting the taps based on observed power consumption. The processor selects a first speed based on the demand signal from the thermostat. The processor identifies a first tap from the mapping based on the first speed and generates the tap selection signal to control the switching circuit to connect power to the first tap.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/374,525, filed Dec. 9, 2016 (now U.S. Pat. No. 10,309,405), whichclaims the benefit of U.S. Provisional Application No. 62/265,645, filedDec. 10, 2015. The entire disclosures of the applications referencedabove are incorporated by reference.

FIELD

The present disclosure relates to control of a multi-speed fan motor andmore particularly to a controller for a circulator blower with multiplespeed taps in a heating, ventilation, and air conditioning (HVAC)system.

BACKGROUND

The background description provided here is for the purpose of generallypresenting the context of the disclosure. Work of the presently namedinventors, to the extent it is described in this background section, aswell as aspects of the description that may not otherwise qualify asprior art at the time of filing, are neither expressly nor impliedlyadmitted as prior art against the present disclosure.

A residential or light commercial HVAC (heating, ventilation, or airconditioning) system controls environmental parameters, such astemperature and humidity, of a building. The target values for theenvironmental parameters, such as a temperature set point, may bespecified by a user or owner of the building, such as an employeeworking in the building or a homeowner.

In FIG. 1, a block diagram of an example HVAC system is presented. Inthis particular example, a forced air system with a gas furnace isshown. Return air is pulled from the building through a filter 104 by acirculator blower 108. In addition, fresh air (sometimes called make upair) may be drawn from outside the building. The circulator blower 108,also referred to as a fan, is controlled by a control board 112. Thecontrol board 112 receives control signals (also referred tointerchangeably as calls, service calls, and demand signals) from athermostat 116. The control board 112 may be powered by incoming ACpower.

For example only, the thermostat 116 may include one or more temperatureset points specified by the user. Based on comparisons between thetemperature set points and a measured temperature, the thermostat 116provides heat and/or cool requests to the control board 112. When a heatrequest is made, the control board 112 causes a burner 120 to ignite.Heat from combustion is introduced to the return air provided by thecirculator blower 108 in a heat exchanger 124. The heated air issupplied to the building and is referred to as supply air.

The burner 120 may include a pilot light, which is a small constantflame for igniting the primary flame in the burner 120. Alternatively,an intermittent pilot may be used in which a small flame is first litprior to igniting the primary flame in the burner 120. A sparker may beused for an intermittent pilot implementation or for direct burnerignition. Another ignition option includes a hot surface igniter, whichheats a surface to a high enough temperature that, when gas isintroduced, the heated surface initiates combustion of the gas. Fuel forcombustion, such as natural gas, may be provided by a gas valve 128.

The products of combustion are exhausted outside of the building, and aninducer blower 132 may be turned on prior to ignition of the burner 120.In a high efficiency furnace, the products of combustion may not be hotenough to have sufficient buoyancy to exhaust via conduction. Therefore,the inducer blower 132 creates a draft to exhaust the products ofcombustion. The inducer blower 132 may remain running while the burner120 is operating. In addition, the inducer blower 132 may continuerunning for a set period of time after the burner 120 turns off.

A single enclosure, which will be referred to as an air handler unit136, may include the filter 104, the circulator blower 108, the controlboard 112, the burner 120, the heat exchanger 124, the inducer blower132, an expansion valve 140, an evaporator 144, and a condensate pan146. In various implementations, the air handler unit 136 includes anelectrical heating device (not shown) instead of or in addition to theburner 120. When used in addition to the burner 120, the electricalheating device may provide backup or secondary heat.

In FIG. 1, the HVAC system includes a split air conditioning system.Refrigerant is circulated through a compressor 148, a condenser 152, theexpansion valve 140, and the evaporator 144. The evaporator 144 isplaced in series with the supply air so that when cooling is desired,the evaporator 144 removes heat from the supply air, thereby cooling thesupply air. During cooling, the evaporator 144 is cold, which causeswater vapor to condense. This water vapor is collected in the condensatepan 146, which drains or is pumped out.

A control module 156 receives a cool request from the control board 112and controls the compressor 148 accordingly. The control module 156 alsocontrols a condenser fan 160, which increases heat exchange between thecondenser 152 and outside air. In such a split system, the compressor148, the condenser 152, the control module 156, and the condenser fan160 are generally located outside of the building, often in a singlecondensing unit 164.

In various implementations, the control module 156 may simply include arun capacitor, a start capacitor, and a contactor or relay. In fact, incertain implementations, the start capacitor may be omitted, such aswhen a scroll compressor instead of a reciprocating compressor is beingused. The compressor 148 may be a variable-capacity compressor and mayrespond to a multiple-level cool request. For example, the cool requestmay indicate a mid-capacity call for cool or a high-capacity call forcool.

The electrical lines provided to the condensing unit 164 may include a240 volt mains power line (not shown) and a 24 volt switched controlline. The 24 volt control line may correspond to the cool request shownin FIG. 1. The 24 volt control line controls operation of the contactor.When the control line indicates that the compressor should be on, thecontactor contacts close, connecting the 240 volt power supply to thecompressor 148. In addition, the contactor may connect the 240 voltpower supply to the condenser fan 160. In various implementations, suchas when the condensing unit 164 is located in the ground as part of ageothermal system, the condenser fan 160 may be omitted. When the 240volt mains power supply arrives in two legs, as is common in the U.S.,the contactor may have two sets of contacts, and can be referred to as adouble-pole single-throw switch.

Monitoring of operation of components in the condensing unit 164 and theair handler unit 136 has traditionally been performed by an expensivearray of multiple discrete sensors that measure current individually foreach component. For example, a first sensor may sense the current drawnby a motor, another sensor measures resistance or current flow of anigniter, and yet another sensor monitors a state of a gas valve.However, the cost of these sensors and the time required forinstallation of, and taking readings from, the sensors has mademonitoring cost-prohibitive.

The thermostat 116 may direct, via the control board 112, whether thecirculator blower 108 is turned on at all times or only when a heatrequest or cool request is present (automatic fan mode). In variousimplementations, the circulator blower 108 can operate at multiplespeeds or at any speed within a predetermined range. One or moreswitching relays (not shown) may be used to control the circulatorblower 108 and/or to select a speed of the circulator blower 108.

SUMMARY

A circulator blower controller for a circulator blower of a heating,ventilation, and air conditioning (HVAC) system of a building includesan interface configured to receive a demand signal from a thermostat.The demand signal specifies an operating mode for the HVAC system. Aswitching circuit configured to, in response to a tap selection signal,selectively connect power to one of a plurality of taps of a motor ofthe circulator blower. A data store configured to store a mapping from aplurality of speeds to the plurality of taps. A processor configured to,for each tap of the plurality of taps, observe power consumed by thecirculator blower while power is connected to the tap by the switchingcircuit. The processor determines the mapping by sorting the taps basedon observed power consumption. The processor selects a first speed basedon the demand signal from the thermostat. The processor identifies afirst tap from the mapping based on the first speed. In response toidentifying the first tap, the processor generates the tap selectionsignal to control the switching circuit to connect power to the firsttap.

In other features, the circulator blower is included in a circulatorblower system. The circulator blower includes (i) the motor and (ii) afan driven by the motor and configured to circulate air within thebuilding. In other features, the motor includes at least one of anelectronically commutated motor (ECM) configured such that each of theplurality of taps instructs the ECM to run at a respective speed. Apermanent split capacitor (PSC) motor including a winding and configuredsuch that each of the plurality of taps corresponds to different pointsalong the winding. In other features, the motor includes the ECM. Aplurality of sensors that determine which of the plurality of taps isactivated. A speed controller configured to control the ECM to rotate ata speed based on which of the plurality of taps is activated. In otherfeatures, the plurality of operating modes includes a cool mode and afan only mode. In other features, the processor is configured to, inresponse to the demand signal specifying the fan only mode, set thefirst speed to a speed defined by a user of the building. In otherfeatures, the plurality of operating modes further includes a heat mode.The processor is configured to, in response to the demand signalspecifying the heat mode, set the first speed to a speed defined by auser of the building.

In other features, in response to the demand signal specifying the coolmode, the processor is configured to select the first speed according toa predetermined initial speed. After a first predetermined period oftime following selection of the first speed, select a second speed thatis faster than the first speed. In response to selection of the secondspeed, the processor is configured to (i) identify a second tap from themapping based on the second speed and (ii) generate the tap selectionsignal to control the switching circuit to connect power to the secondtap. In other features, the predetermined initial speed is a lowestspeed of the circulator blower. In other features, in response to thedemand signal specifying the cool mode, the processor is configured to,after a second predetermined period of time following selection of thesecond speed, select a third speed that is faster than the second speed.In response to selection of the third speed, the processor is configuredto (i) identify a third tap from the mapping based on the third speedand (ii) generate the tap selection signal to control the switchingcircuit to connect power to the third tap.

In other features, in response to the demand signal specifying the coolmode, the processor is configured to select the first speed according toa predetermined initial speed. The processor is configured to evaluatean operating condition of the HVAC system. The processor is configuredto, in response to the operating condition of the HVAC system meeting afirst predetermined criterion, select a second speed that is faster thanthe first speed. The processor is configured to, in response toselection of the second speed, identify a second tap from the mappingbased on the second speed and generate the tap selection signal tocontrol the switching circuit to connect power to the second tap. Inother features, the operating condition of the HVAC system istemperature split. The temperature split is based on a differencebetween supply air leaving an evaporator coil of the HVAC system andreturn air arriving at the evaporator coil. The processor is configuredto integrate time periods during which the temperature split divergedfrom a predetermined temperature profile. The first predeterminedcriterion is the integration exceeding a first threshold. In otherfeatures, the processor is configured to, in response to determiningthat a humidity in a conditioned space of the building exceeds a desiredhumidity, increase the first threshold.

In other features, the processor is configured to perform theintegration by, for each time period during which the temperature splitdiverged from the predetermined temperature profile, adding a product ofa gain factor and a length of the time period to an accumulatorregister. In other features, the processor is configured to, in responseto selection of the second speed, (i) evaluate the operating conditionof the HVAC system and, (ii) in response to the operating condition ofthe HVAC system meeting a second predetermined criterion, select a thirdspeed that is faster than the second speed. In response to selection ofthe third speed, the processor is configured to (i) identify a third tapfrom the mapping based on the third speed and (ii) generate the tapselection signal to control the switching circuit to connect power tothe third tap. The second predetermined criterion is the integrationexceeding a second threshold. In other features, the processor isconfigured to, after a first predetermined period of time followingselection of the first speed, select the second speed.

In other features, the processor is configured to, in response todetermining that a humidity in a conditioned space of the buildingexceeds a desired humidity, increase the first predetermined period oftime. In other features, in response to the demand signal specifying thecool mode, the processor is configured to selectively determine arefrigerant undercharge condition of the HVAC system. In response todetermining the refrigerant undercharge condition, the processor isconfigured to (i) select a slower speed, (ii) identify a second tap fromthe mapping based on the slower speed, and (iii) generate the tapselection signal to control the switching circuit to connect power tothe second tap. In other features, the processor is configured to, untilthe mapping includes entries for all of the plurality of taps, observethe power consumed. Observing the power consumed includes, while nodemand signal is received from the thermostat, iterating through taps ofthe plurality of taps by generating the tap selection signal to controlthe switching circuit to connect power to an evaluation tap andobserving the power consumed while power is connected to the evaluationtap. In other features, the processor is configured to generate the tapselection signal to control the switching circuit to connect power to asecond tap in response to determining that the motor is not operatingwhile power is connected to the first tap.

A method of controlling a motor in a heating, ventilation, and airconditioning (HVAC) system of a building, the method includes receivinga demand signal from a thermostat. The demand signal specifies anoperating mode for the HVAC system. In response to a tap selectionsignal, the method includes selectively connecting power to one of aplurality of taps of the motor. The method includes storing a mappingfrom a plurality of speeds to the plurality of taps. The method includesfor each tap of the plurality of taps, observing power consumed by themotor while power is connected to the tap by a switching circuit. Themethod includes determining the mapping by sorting the taps based onobserved power consumption. The method includes selecting a first speedbased on the demand signal from the thermostat. The method includesidentifying a first tap from the mapping based on the first speed. Themethod includes, in response to identifying the first tap, generatingthe tap selection signal to control the switching circuit to connectpower to the first tap.

In other features, the motor drives a fan configured to circulate airwithin the building. In other features, the plurality of operating modesincludes a cool mode and a fan only mode. In other features, the methodincludes, in response to the demand signal specifying the fan only mode,setting the first speed to a speed defined by a user of the building. Inother features, the plurality of operating modes further includes a heatmode. The method includes, in response to the demand signal specifyingthe heat mode, setting the first speed to a speed defined by a user ofthe building. In other features, the method includes, in response to thedemand signal specifying the cool mode. The method includes selectingthe first speed according to a predetermined initial speed. After afirst predetermined period of time following selection of the firstspeed, the method includes selecting a second speed that is faster thanthe first speed. In response to selection of the second speed, themethod includes (i) identifying a second tap from the mapping based onthe second speed and (ii) generating the tap selection signal to controlthe switching circuit to connect power to the second tap. In otherfeatures, the predetermined initial speed is a lowest speed of themotor.

In other features, the method includes, in response to the demand signalspecifying the cool mode, after a second predetermined period of timefollowing selection of the second speed, selecting a third speed that isfaster than the second speed. In response to selection of the thirdspeed, the method includes (i) identifying a third tap from the mappingbased on the third speed and (ii) generating the tap selection signal tocontrol the switching circuit to connect power to the third tap. Inother features, the method includes, in response to the demand signalspecifying the cool mode, selecting the first speed according to apredetermined initial speed. The method includes evaluating an operatingcondition of the HVAC system. In response to the operating condition ofthe HVAC system meeting a first predetermined criterion, the methodincludes selecting a second speed that is faster than the first speed.In response to selection of the second speed, the method includes (i)identifying a second tap from the mapping based on the second speed and(ii) generating the tap selection signal to control the switchingcircuit to connect power to the second tap. In other features, theoperating condition of the HVAC system is temperature split. Thetemperature split is based on a difference between supply air leaving anevaporator coil of the HVAC system and return air arriving at theevaporator coil. The method includes integrating time periods duringwhich the temperature split diverged from a predetermined temperatureprofile. The first predetermined criterion is the integration exceedinga first threshold.

In other features, the method includes, in response to determining thata humidity in a conditioned space of the building exceeds a desiredhumidity, increasing the first threshold. In other features, the methodincludes perform the integration by, for each time period during whichthe temperature split diverged from the predetermined temperatureprofile, adding a product of a gain factor and a length of the timeperiod to an accumulator register. In other features, the methodincludes, in response to selection of the second speed, (i) evaluatingthe operating condition of the HVAC system and (ii) in response to theoperating condition of the HVAC system meeting a second predeterminedcriterion, selecting a third speed that is faster than the second speed.In response to selection of the third speed, the method include (i)identifying a third tap from the mapping based on the third speed and(ii) generating the tap selection signal to control the switchingcircuit to connect power to the third tap. The second predeterminedcriterion is the integration exceeding a second threshold. In otherfeatures, the method includes, after a first predetermined period oftime following selection of the first speed, selecting the second speed.

In other features, the method includes, in response to determining thata humidity in a conditioned space of the building exceeds a desiredhumidity, increasing the first predetermined period of time. In otherfeatures, the method includes, in response to the demand signalspecifying the cool mode, selectively determining a refrigerantundercharge condition of the HVAC system. In response to determining therefrigerant undercharge condition, the method (i) selecting a slowerspeed, (ii) identifying a second tap from the mapping based on theslower speed, and (iii) generating the tap selection signal to controlthe switching circuit to connect power to the second tap. In otherfeatures, the method includes, until the mapping includes entries forall of the plurality of taps, observing the power consumed. The methodincludes observing the power consumed includes, while no demand signalis received from the thermostat, iterating through taps of the pluralityof taps by generating the tap selection signal to control the switchingcircuit to connect power to an evaluation tap and observing the powerconsumed while power is connected to the evaluation tap. In otherfeatures, the method includes generating the tap selection signal tocontrol the switching circuit to connect power to a second tap inresponse to determining that the motor is not operating while power isconnected to the first tap.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description, the claims, and the drawings.The detailed description and specific examples are intended for purposesof illustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings.

FIG. 1 is a block diagram of an example HVAC system according to theprior art.

FIG. 2A is a functional block diagram of an example HVAC systemincluding an implementation of an air handler monitor module and a motorcontrol circuitry.

FIG. 2B is a functional block diagram of an example HVAC systemincluding an implementation of a condensing monitor module.

FIG. 2C is a functional block diagram of an example HVAC system based ona heat pump.

FIG. 3 is a high level functional block diagram of an example systemincluding an implementation of a remote monitoring system.

FIG. 4 is a schematic diagram of example motor control circuitry fordriving a fan with up to five taps.

FIG. 5 is a schematic diagram of example motor control circuitry fordriving a fan with up to four taps.

FIG. 6 is a functional block diagram of an example motor systemincluding three taps corresponding to three motor speeds.

FIG. 7A is a configuration diagram of an example 3-tap Permanent SplitCapacitor (PSC) motor.

FIG. 7B is a configuration diagram of an example 3-tap electronicallycommutated Motor (ECM).

FIG. 8A and FIG. 8B together are a flowchart of example time-basedstaging operation of an example HVAC system including motor controlcircuitry.

FIG. 9A and FIG. 9B together are a flowchart of exampletemperature-based staging operation for a call for cooling.

FIG. 10 is a flowchart of example operation for mapping motor taps tofan speeds.

FIG. 11 is a temperature split versus time graph of an example HVACsystem using a single fan speed for cooling.

FIG. 12 is a temperature split versus time graph of an example HVACsystem having motor control circuitry configured to actively manage thefan speed.

FIG. 13 is a speed versus time graph of an example HVAC system with a5-speed motor and motor control circuitry configured to actively managethe fan speed.

FIG. 14A and FIG. 14B together are a flowchart of an example process forsetting the times for the fan to transition between speeds.

In the drawings, reference numbers may be reused to identify similarand/or identical elements.

DETAILED DESCRIPTION Monitoring System

According to the present disclosure, a circulator blower controller canbe integrated with a residential or light commercial HVAC (heating,ventilation, or air conditioning) system of a building. The circulatorblower controller can control motor speeds of a circulator blower byconnecting to one of a plurality of taps of the motor such to therebyimprove the performance and/or efficiency of the HVAC system.

As used in this application, the term HVAC can encompass allenvironmental comfort systems in a building, including heating, cooling,humidifying, dehumidifying, and air exchanging and purifying, and coversdevices such as furnaces, heat pumps, humidifiers, dehumidifiers, andair conditioners. HVAC systems as described in this application do notnecessarily include both heating and air conditioning, and may insteadhave only one or the other.

In split HVAC systems with an air handler unit (often, located indoors)and a condensing unit (often, located outdoors), an air handler monitormodule and a condensing monitor module, respectively, can be used. Theair handler monitor module and the condensing monitor module may beintegrated by the manufacturer of the HVAC system, may be added at thetime of the installation of the HVAC system, and/or may be retrofittedto an existing HVAC system.

In heat pump systems, the function of the air handler unit and thecondensing unit are reversed depending on the mode of the heat pump. Asa result, although the present disclosure uses the terms air handlerunit and condensing unit, the terms indoor unit and outdoor unit couldbe used instead in the context of a heat pump. The terms indoor unit andoutdoor unit emphasize that the physical locations of the componentsstay the same while their roles change depending on the mode of the heatpump. A reversing valve selectively reverses the flow of refrigerantfrom what is shown in FIG. 1 depending on whether the system is heatingthe building or cooling the building. When the flow of refrigerant isreversed, the roles of the evaporator and condenser are reversed—i.e.,refrigerant evaporation occurs in what is labeled the condenser whilerefrigerant condensation occurs in what is labeled as the evaporator.

The air handler monitor and condensing monitor modules monitor operatingparameters of associated components of the HVAC system. For example, theoperating parameters may include operation status, refrigerant chargecondition, airflow, return/supply air temperature split, humidity ofinside and outside air, power supply current, power supply voltage,operating and ambient temperatures of inside and outside air,refrigerant temperatures at various points in the refrigerant loop,fault signals, and control signals.

The principles of the present disclosure may be applied to control motorspeed of other circulator blower machines. A motor control circuitry maybe integrated within the air handler unit to control the motor speed ofthe circulator blower machine based on the operating parameters providedby the monitoring system.

The air handler monitor and condensing monitor modules may communicatedata between each other, while one or both of the air handler monitorand condensing monitor modules upload data to a remote location, ordownload data from a remote location. The remote location may beaccessible via any suitable network, including the Internet.

The remote location includes one or more computers, which will bereferred to as servers. The servers execute a monitoring system onbehalf of a monitoring company. The monitoring system receives andprocesses the data from the air handler monitor and condensing monitormodules of customers who have such systems installed. The monitoringsystem can provide performance information, diagnostic alerts, and errormessages to a customer and/or third parties, such as designated HVACcontractors.

The remote location may also include a cloud, which will be referred toas remote storage. The monitoring system receives profile data from theremote storage and provides the profile data for staging operation ofthe HVAC system when a call for cool is received.

A server of the monitoring system includes a processor and memory. Thememory stores application code that processes data received from the airhandler monitor and condensing monitor modules and determines existingand/or impending failures, as described in more detail below. Theprocessor executes this application code and stores received data eitherin the memory or in other forms of storage, including magnetic storage,optical storage, flash memory storage, etc. While the term server isused in this application, the application is not limited to a singleserver.

A collection of servers may together operate to receive and process datafrom the air handler monitor and condensing monitor modules of multiplebuildings. A load balancing algorithm may be used between the servers todistribute processing and storage. The present application is notlimited to servers that are owned, maintained, and housed by amonitoring company. Although the present disclosure describesdiagnostics and processing and alerting occurring in a remote monitoringsystem, some or all of these functions may be performed locally usinginstalled equipment and/or customer resources, such as on a customercomputer or computers.

Based on measurements from the air handler monitor and condensingmonitor modules, the monitoring company can determine a status of theHVAC system and can change the fan motor speed of the HVAC system whenthe status of the HVAC system is abnormal. This status may be measuredfor the system as a whole, such as in terms of efficiency, refrigerantcharge, etc., and/or may be monitored for one or more individualcomponents, such as tap order/condition of a fan motor, airflow of theevaporator, return/supply air temperature split of an air handler unit,humidity of inside and outside air, operating and ambient temperaturesof inside and outside air, refrigerant temperatures at various points inthe refrigerant loop, fault signals, and control signals.

In addition, the monitoring system may detect abnormal configuration ofthe fan motor, such as a tap failure or taps of the fan motor connectedout of order. When a failure is detected, the motor control circuitrycan be notified and potential remediation steps can be takenimmediately. For example, a different tap of the fan motor may beselected and the selected tap connected to operate the fan motor at adifferent speed.

FIGS. 2A-2B are functional block diagrams of an example air handler unit136 including a motor control circuitry 202 and a monitoring systemassociated with an HVAC system of a building. The air handler unit 136of FIG. 1 is shown for reference. Because the monitoring systems of thepresent disclosure can be used in retrofit applications, elements of theair handler unit 136 may remain unmodified. An air handler monitormodule 200 and a condensing monitor module 204 can be installed in anexisting system without needing to replace the original thermostat 116shown in FIG. 1. To enable certain additional functionality, however,such as WiFi thermostat control and/or thermostat display of alertmessages, the thermostat 116 of FIG. 1 may be replaced with a thermostat208 having networking capability.

In many systems, the air handler unit 136 is located inside thebuilding, while the condensing unit 164 is located outside the building.The present disclosure is not limited, and applies to other systemsincluding, as examples only, systems where the components of the airhandler unit 136 and the condensing unit 164 are located in closeproximity to each other or even in a single enclosure. The singleenclosure may be located inside or outside of the building. In variousimplementations, the air handler unit 136 may be located in a basement,garage, or attic. In ground source systems, where heat is exchanged withthe earth, the air handler unit 136 and the condensing unit 164 may belocated near the earth, such as in a basement, crawlspace, garage, or onthe first floor, such as when the first floor is separated from theearth by only a concrete slab.

In FIG. 2A, the air handler monitor module 200 is shown external to theair handler unit 136, although the air handler monitor module 200 may bephysically located outside of, in contact with, or even inside of anenclosure, such as a sheet metal casing, of the air handler unit 136.

When installing the air handler monitor module 200 in the air handlerunit 136, power is provided to the air handler monitor module 200. Forexample, a transformer 212 can be connected to an AC line in order toprovide AC power to the air handler monitor module 200. The air handlermonitor module 200 may measure voltage of the incoming AC line based onthis transformed power supply. For example, the transformer 212 may be a10-to-1 transformer and therefore provide either a 12V or 24V AC supplyto the air handler monitor module 200 depending on whether the airhandler unit 136 is operating on nominal 120 volt or nominal 240 voltpower. The air handler monitor module 200 then receives power from thetransformer 212 and determines the AC line voltage based on the powerreceived from the transformer 212. In various implementations, thetransformer 212 may be eliminated, powering the air handler monitormodule 200 directly from incoming AC power. In such cases, power-linecommunications may be conducted over the incoming AC power lines ratherthan the thermostat control signals.

A current sensor 216 measures incoming current to the air handler unit136. The current sensor 216 may include a current transformer that snapsaround one power lead of the incoming AC power. The current sensor 216may alternatively include a current shunt or a hall effect device. Invarious implementations, a power sensor (not shown) may be used inaddition to or in place of the current sensor 216.

In various other implementations, electrical parameters (such asvoltage, current, and power factor) may be measured at a differentlocation, such as at an electrical panel providing power to the buildingfrom the electrical utility.

The control board 112 is also powered by the transformer 212 andconnected to the motor control circuitry 202 and sensors of the airhandler unit 136. For simplicity of illustration, routing of the ACpower to various powered components of the air handler unit 136, such asthe circulator blower 108, the gas valve 128, and the inducer blower132, are not shown. The current sensor 216 measures the current enteringthe air handler unit 136 and therefore represents an aggregate currentof the current-consuming components of the air handler unit 136.

The control board 112 controls tap selection of the circulator blower108 in response to signals from a thermostat 208 received over controllines and/or in response to signals from the air handler monitor module200 over tap control line. The air handler monitor module 200 monitorsthe control lines. The control lines may carry a call for cool, a callfor heat, and a call for fan. The control lines may include a linecorresponding to a state of a reversing valve in heat pump systems.

The control lines may further carry calls for secondary heat and/orsecondary cooling, which may be activated when the primary heating orprimary cooling is insufficient. In dual fuel systems, such as systemsoperating from either electricity or natural gas, control signalsrelated to the selection of the fuel may be monitored. Further,additional status and error signals may be monitored, such as operationstatus, refrigerant charge condition, airflow, return/supply airtemperature split, humidity of inside and outside air, operating andambient temperatures of inside and outside air, refrigerant temperaturesat various points in the refrigerant loop, fault signals (e.g., tapfailure, out of order tap configuration, closed vent, etc.), a defroststatus signal, which may be asserted when the compressor is shut off anda defrost heater operates to melt frost from an evaporator.

The control lines may be monitored by attaching leads to terminal blocksat the control board 112 at which the fan and heat signals are received.These terminal blocks may include additional connections where leads canbe attached between these additional connections and the air handlermonitor module 200. Alternatively, leads from the air handler monitormodule 200 may be attached to the same location as the fan and heatsignals, such as by putting multiple spade lugs underneath a signalscrew head.

In various implementations, the cool signal from the thermostat 208 maybe disconnected from the control board 112 and attached to the airhandler monitor module 200. The air handler monitor module 200 can thenprovide a switched cool signal to the control board 112. This allows theair handler monitor module 200 to interrupt operation of the airconditioning system, such as upon detection of water by one of the watersensors. The air handler monitor module 200 may also interrupt operationof the air conditioning system based on information from the condensingmonitor module 204, such as detection of a locked rotor condition in thecompressor.

In various implementations, the air handler monitor module 200 canprovide tap control signals to the motor control circuitry 202 toconnect the fan motor to a selected tap to thereby operate the fan motorat a speed according to a speed map in response to the operating statusof the HVAC system and/or the sensed ambient condition. The speed mapcan be constructed for the fan motor of the circulator blower 108 byinvoking staging operations. The plurality of taps of the fan motor mayfurther be sorted according to the speed map and labeled with the sortedorders.

In various implementations, tap sensors 206 (such as voltage sensors)may be located on each of the plurality taps of the circulator blower108 to detect a tap failure or a tap connection status. For example, thetap sensor 206 may indicate to the air handler monitor module 200whether the power for each individual lead from the motor controlcircuitry is reaching the corresponding tap on the circulator blower108. In other implementations, the tap sensors 206 may be eliminated.

A condensate sensor 220 measures condensate levels in the condensate pan146. If a level of condensate gets too high, this may indicate a plug orclog in the condensate pan 146 or a problem with hoses or pumps used fordrainage from the condensate pan 146. The condensate sensor 220 may beinstalled along with the air handler monitor module 200 or may alreadybe present. When the condensate sensor 220 is already present, anelectrical interface adapter may be used to allow the air handlermonitor module 200 to receive the readings from the condensate sensor220. Although shown in FIG. 2A as being internal to the air handler unit136, access to the condensate pan 146, and therefore the location of thecondensate sensor 220, may be external to the air handler unit 136.

Additional water sensors, such as a conduction (wet floor) sensor mayalso be installed. The air handler unit 136 may be located on a catchpan, especially in situations where the air handler unit 136 is locatedabove living space of the building. The catch pan may include a floatswitch. When enough liquid accumulates in the catch pan, the floatswitch provides an over-level signal, which may be sensed by the airhandler monitor module 200.

A return air sensor 224 is located in a return air plenum 228. Thereturn air sensor 224 may measure temperature and may also measure massairflow. In various implementations, a thermistor may be multiplexed asboth a temperature sensor and a hot wire mass airflow sensor. In variousimplementations, the return air sensor 224 is upstream of the filter 104but downstream of any bends in the return air plenum 228.

A supply air sensor 232 is located in a supply air plenum 236. Thesupply air sensor 232 may measure air temperature and may also measuremass airflow. The supply air sensor 232 may include a thermistor that ismultiplexed to measure both temperature and, as a hot wire sensor, massairflow. In various implementations, such as is shown in FIG. 2A, thesupply air sensor 232 may be located downstream of the evaporator 144but upstream of any bends in the supply air plenum 236.

In various implementations, only one of the return air sensor 224 and/orthe supply air sensor 232 is present. In various implementations, thereturn air sensor 224 and/or the supply air sensor 232 may be able tomeasure both temperature and humidity. In such implementations, a massairflow sensor may be installed along with one or both of the return airsensor 224 and the supply air sensor 232. For example, a mass airflowsensor and the return air sensor 224 may be contained in a package andinstalled into the return air plenum 228 as one unit.

A differential pressure reading may be obtained by placing oppositesensing inputs of a differential pressure sensor (not shown) in thereturn air plenum 228 and the supply air plenum 236, respectively. Forexample only, these sensing inputs may be collocated or integrated withthe return air sensor 224 and the supply air sensor 232, respectively.In various implementations, discrete pressure sensors may be placed inthe return air plenum 228 and the supply air plenum 236. A differentialpressure value can then be calculated by subtracting the individualpressure values.

The air handler monitor module 200 also receives a suction linetemperature from a suction line temperature sensor 240. The suction linetemperature sensor 240 measures refrigerant temperature in therefrigerant line between the evaporator 144 of FIG. 2A and thecompressor 148 of FIG. 2B. A liquid line temperature sensor 244 measuresthe temperature of refrigerant in a liquid line traveling from thecondenser 152 of FIG. 2B to the expansion valve 140 of FIG. 2A.

The air handler monitor module 200 may include one or more expansionports to allow for connection of additional sensors and/or to allowconnection to other devices, such as a home security system, aproprietary handheld device for use by contractors, or a portablecomputer.

The air handler monitor module 200 also monitors control signals fromthe thermostat 208. Because one or more of these control signals is alsotransmitted to the condensing unit 164 of FIG. 2B, these control signalscan be used for communication between the air handler monitor module 200and the condensing monitor module 204 of FIG. 2B.

The air handler monitor module 200 may transmit frames of datacorresponding to periods of time. For example only, 7.5 frames may spanone second (i.e., 0.1333 seconds per frame). Each frame of data mayinclude voltage, current, temperatures, control line status, and watersensor status. Calculations may be performed for each frame of data,including averages, powers, RMS, and FFT. Then the frame is transmittedto the monitoring system.

In various implementations, the air handler monitor module 200 may onlytransmit frames during certain periods of time. These periods may becritical to operation of the HVAC system. For example, when thermostatcontrol lines change, the air handler monitor module 200 may record dataand transmit frames for a predetermined period of time after thattransition. Then, if the HVAC system is operating, the air handlermonitor module 200 may intermittently record data and transmit framesuntil operation of the HVAC system has completed.

The air handler monitor module 200 transmits data measured by both theair handler monitor module 200 itself and the condensing monitor module204 over a wide area network 248, such as the Internet (referred to asthe Internet 248). The air handler monitor module 200 may access theInternet 248 using a router 252 of the customer. The customer router 252may already be present to provide Internet access to other devices (notshown) within the building, such as a customer computer and/or variousother devices having Internet connectivity, such as a DVR (digital videorecorder) or a video gaming system.

The air handler monitor module 200 communicates with the customer router252 using a proprietary or standardized, wired or wireless protocol,such as Bluetooth, ZigBee (IEEE 802.15.4), 900 Megahertz, 2.4 Gigahertz,WiFi (IEEE 802.11). In various implementations, a gateway 256 isimplemented, which creates a wireless network with the air handlermonitor module 200. The gateway 256 may interface with the customerrouter 252 using a wireless or wired protocol, such as Ethernet (IEEE802.3). In some implementations, the air handler monitor module 200 maycommunicate with the gateway 256 using power-line communications.

The thermostat 208 may also communicate with the customer router 252using WiFi. Alternatively, the thermostat 208 may communicate with thecustomer router 252 via the gateway 256. In various implementations, theair handler monitor module 200 and the thermostat 208 do not communicatedirectly. However, because they are both connected through the customerrouter 252 to a remote monitoring system, the remote monitoring systemmay allow for control of one based on inputs from the other. Forexample, various faults identified based on information from the airhandler monitor module 200 may cause the remote monitoring system toadjust temperature set points of the thermostat 208 and/or displaywarning or alert messages on the thermostat 208.

In various implementations, the transformer 212 may be omitted, and theair handler monitor module 200 may include a power supply that isdirectly powered by the incoming AC power. Further, power-linecommunications may be conducted over the AC power line instead of over alower-voltage HVAC control line.

In various implementations, the current sensor 216 may be omitted, andinstead a voltage sensor (not shown) may be used. The voltage sensormeasures the voltage of an output of a transformer internal to thecontrol board 112, the internal transformer providing the power (e.g.,24 Volts) for the control signals. The air handler monitor module 200may measure the voltage of the incoming AC power and calculate a ratioof the voltage input to the internal transformer to the voltage outputfrom the internal transformer. As the current load on the internaltransformer increases, the impedance of the internal transformer causesthe voltage of the output power to decrease. Therefore, the current drawfrom the internal transformer can be inferred from the measured ratio(also called an apparent transformer ratio). The inferred current drawmay be used in place of the measured aggregate current draw described inthe present disclosure.

In FIG. 2B, the condensing monitor module 204 is installed in thecondensing unit 164. A transformer 260 converts incoming AC voltage intoa stepped-down voltage for powering the condensing monitor module 204.In various implementations, the transformer 260 may be a 10-to-1transformer. A current sensor 264 measures current entering thecondensing unit 164. The condensing monitor module 204 may also measurevoltage from the supply provided by the transformer 260. Based onmeasurements of the voltage and current, the condensing monitor module204 may calculate power and/or may determine power factor. In variousimplementations, the transformer 212 may be eliminated, powering thecondensing unit 164 directly from incoming AC power. In such cases,power-line communications may be conducted over the incoming AC powerlines rather than the thermostat control signals.

A liquid line temperature sensor 244 measures the temperature ofrefrigerant traveling from the condenser 152 to the air handler unit136. In various implementations, the liquid line temperature sensor 244is located prior to any filter-drier (not shown).

In various implementations, the condensing monitor module 204 mayreceive ambient temperature data from a temperature sensor (not shown).When the condensing monitor module 204 is located outdoors, the ambienttemperature represents an outside ambient temperature. The temperaturesensor supplying the ambient temperature may be located outside of anenclosure of the condensing unit 164. Alternatively, the temperaturesensor may be located within the enclosure, but exposed to circulatingair. In various implementations the temperature sensor may be shieldedfrom direct sunlight and may be exposed to an air cavity that is notdirectly heated by sunlight. Alternatively or additionally, online(including Internet-based) weather data based on geographical locationof the building may be used to determine sun load, outside ambient airtemperature, precipitation, and humidity.

In various implementations, the condensing monitor module 204 mayreceive refrigerant temperature data from refrigerant temperaturesensors (not shown) located at various points, such as before thecompressor 148 (referred to as a suction line temperature), after thecompressor 148 (referred to as a compressor discharge temperature),after the condenser 152 (referred to as a liquid line out temperature),and/or at one or more points along a coil of the condenser 152. Thelocation of temperature sensors may be dictated by a physicalarrangement of the condenser coils. Additionally or alternatively to theliquid line out temperature sensor, a liquid line in temperature sensormay be used. An approach temperature may be calculated, which is ameasure of how close the condenser 152 has been able to bring the liquidline out temperature to the ambient air temperature.

During installation, the location of the temperature sensors may berecorded. Additionally or alternatively, a database may be maintainedthat specifies where temperature sensors are placed. This database maybe referenced by installers and may allow for accurate remote processingof the temperature data. The database may be used for both air handlersensors and compressor/condenser sensors. The database may beprepopulated by the monitoring company or may be developed by trustedinstallers, and then shared with other installation contractors.

As described above, the condensing monitor module 204 may communicatewith the air handler monitor module 200 over one or more control linesfrom the thermostat 208. In these implementations, data from thecondensing monitor module 204 is transmitted to the air handler monitormodule 200, which in turn uploads the data over the Internet 248.

In various implementations, the transformer 260 may be omitted, and thecondensing monitor module 204 may include a power supply that isdirectly powered by the incoming AC power. Further, power-linecommunications may be conducted over the AC power line instead of over alower-voltage HVAC control line.

In FIG. 2C, an example condensing unit 268 is shown for a heat pumpimplementation. The condensing unit 268 may be configured similarly tothe condensing unit 164 of FIG. 2B. Similarly to FIG. 2B, thetransformer 260 may be omitted in various implementations. Althoughreferred to as the condensing unit 268, the mode of the heat pumpdetermines whether the condenser 152 of the condensing unit 268 isactually operating as a condenser or as an evaporator. A reversing valve272 is controlled by a control module 276 and determines whether thecompressor 148 discharges compressed refrigerant toward the condenser152 (cooling mode) or away from the condenser 152 (heating mode).

In various implementations, a current sensor 280 is implemented tomeasure one or more currents of the control signals. The current sensor280 may measure an aggregate current of all the control lines arrivingat the condensing unit 268. The aggregate current may be obtained bymeasuring the current of a common control return conductor. Theaggregate current measured by the current sensor 280 may be used todetermine the state of multiple heat pump control signals, such assignals that control operation of defrosting functions and the reversingvalve. The aggregate current measured by the current sensor 280 may alsobe used to determine the state of calls for varying levels of compressorcapacity. While not shown, the current sensor 280 may similarly beinstalled in the condensing unit 164.

In FIG. 3, the air handler monitor module 200 and the thermostat 208 areshown communicating, using the customer router 252, with a remotemonitoring system 304 via the Internet 248. In various implementations,the remote monitoring system may transmit data from a remote storage tothe monitoring server for staging operations. For example, profilesincluding timing factors and/or gains factors for determining whether toswitch the tap for a different fan motor speed during the stagingoperations. In other implementations, the condensing monitor module 204may transmit data from the air handler monitor module 200 and thecondensing monitor module 204 to an external wireless receiver. Theexternal wireless receiver may be a proprietary receiver for aneighborhood in which the building is located, or may be aninfrastructure receiver, such as a metropolitan area network (such asWiMAX), a WiFi access point, or a mobile phone base station.

The remote monitoring system 304 includes a monitoring server 308 thatreceives data from the air handler monitor module 200 and the thermostat208 and maintains and verifies network continuity with the air handlermonitor module 200. The monitoring server 308 executes variousalgorithms to identify problems and/or solve problems, such as failuresor decreased efficiency, refrigerant undercharge condition, tap failure,closed vent(s), abnormal return/supply air temperature split, deviationfrom desired humidity, and/or taps on the fan motor connected out oforder.

The monitoring server 308 may notify a review server 312 when a problemis identified or a fault is predicted. This programmatic assessment maybe referred to as an advisory. Some or all advisories may be triaged bya technician to reduce false positives and potentially supplement ormodify data corresponding to the advisory. For example, a techniciandevice 316 operated by a technician is used to review the advisory andto monitor data (in various implementations, in real-time) from the airhandler monitor module 200 via the monitoring server 308.

The technician using the technician device 316 reviews the advisory. Ifthe technician determines that the problem or fault is either alreadypresent or impending, the technician instructs the review server 312 tosend an alert to either or both a contractor device 320 or a customerdevice 324. The technician may determine that, although a problem orfault is present, the cause is more likely to be something differentthan specified by the automated advisory. The technician can thereforeissue a different alert or modify the advisory before issuing an alertbased on the advisory. The technician may also annotate the alert sentto the contractor device 320 and/or the customer device 324 withadditional information that may be helpful in identifying the urgency ofaddressing the alert and presenting data that may be useful fordiagnosis or troubleshooting.

In various implementations, minor problems may be reported to thecontractor device 320 only so as not to alarm the customer or inundatethe customer with alerts. Whether the problem is considered to be minormay be based on a threshold. For example, an efficiency decrease greaterthan a predetermined threshold may be reported to both the contractorand the customer, while an efficiency decrease less than thepredetermined threshold is reported to only the contractor.

In some circumstances, the technician may determine that an alert is notwarranted based on the advisory. The advisory may be stored for futureuse, for reporting purposes, and/or for adaptive learning of advisoryalgorithms and thresholds. In various implementations, a majority ofgenerated advisories may be closed by the technician without sending analert.

Based on data collected from advisories and alerts, certain alerts maybe automated. For example, analyzing data over time may indicate thatwhether a certain alert is sent by a technician in response to a certainadvisory depends on whether a data value is on one side of a thresholdor another. A heuristic can then be developed that allows thoseadvisories to be handled automatically without technician review. Basedon other data, it may be determined that certain automatic alerts had afalse positive rate over a threshold. These alerts may be put back underthe control of a technician.

In various implementations, the technician device 316 may be remote fromthe remote monitoring system 304 but connected via a wide area network.For example only, the technician device 316 may include a computingdevice such as a laptop, desktop, or tablet.

With the contractor device 320, the contractor can access a contractorportal 328, which provides historical and real-time data from the airhandler monitor module 200. The contractor using the contractor device320 may also contact the technician using the technician device 316. Thecustomer using the customer device 324 may access a customer portal 332in which a graphical view of the system status as well as alertinformation is shown. The contractor portal 328 and the customer portal332 may be implemented in a variety of ways according to the presentdisclosure, including as an interactive web page, a computerapplication, and/or an app for a smartphone or tablet.

In various implementations, data shown by the customer portal may bemore limited and/or more delayed when compared to data visible in thecontractor portal 328. In various implementations, the contractor device320 can be used to request data from the air handler monitor module 200,such as when commissioning a new installation.

In various implementations, some of all of the functionality of theremote monitoring system 304 may be local instead of remote from thebuilding. For example only, some or all of the functionality may beintegrated with the air handler monitor module 200 or the condensingmonitor module 204. Alternatively, a local controller may implement someof all of the functionality of the remote monitoring system 304.

Detection of various faults may require knowledge of which mode the HVACsystem is operating in, and more specifically, which mode has beencommanded by the thermostat. A heating fault may be identified when, fora given call for heat pattern, the supply/return air temperature splitindicates insufficient heating. The threshold may be set at apredetermined percentage of the expected supply/return air temperaturesplit. For additional discussion of fault/failure detection using theabove system, see U.S. patent application Ser. No. 14/212,632, filedMar. 14, 2014, with first-named inventor Jeffrey Arensmeier, titled“HVAC System Remote Monitoring and Diagnosis,” the entire disclosure ofwhich is incorporated by reference.

Returning back to FIG. 2A, in order for the monitoring system todetermine which mode the HVAC system is operating in, each controlsignal between the thermostat 208 and the control board 112 may bemonitored. Because the monitoring system of the present disclosure canbe used in a retrofit environment, this may require connecting leads toeach of the control lines. Making individual connections requiresadditional installation time and therefore expense. As the number ofconnections increase, the number of opportunities for a looseconnection, and therefore erroneous readings, increase.

Further, because connecting leads may require removing and reattachingcontrol lines from the control module, the loose connection may evenaffect normal operation of the HVAC system, such as the ability of thethermostat 208 to control certain aspects of the control board 112.Further, a location at which the control lines are accessible may bedifficult for an installer to reach without removing other components ofthe HVAC system, which increases installation time and also increasesthe risk of introducing problems.

With multiple connections, even when the control lines are successfullyconnected, there is a risk that the connections will bemisidentified—e.g., leading the monitoring system to believe that a callfor cool has been made by the thermostat 208 when, in fact, a call forheat was instead made. Some HVAC systems may use those control lines ina non-standard way. Again, this may lead to misinterpretation of thecontrol signals by the monitoring system. A further complication isintroduced by “communicating systems,” which do not rely on standardHVAC control lines and instead multiplex multiple signals onto one ormore control lines. For example only, in a communicating system thethermostat 208 and the control board 112 may perform bidirectionaldigital communication using two or more lines. As a result, individualcontrol lines corresponding to each mode of operation of the HVAC systemmay not be present.

The present disclosure presents an alternative to individually sensingthe control lines and this alternative may eliminate or mitigate some orall of the issues identified above. When the thermostat 208 makes a callfor heat, one or more components of the HVAC system will draw a currentto service the call for heat. For example, a relay (not shown) may beenergized to open the gas valve 128. Meanwhile, when a call for cool ismade by the thermostat 208, other components may draw a current—forexample, a relay may control the control module 156.

The current consumed by these various devices may be different. Forexample, the current required to close a switch of the control module156 may be greater than the current required to open the gas valve 128.An aggregate control line current may therefore uniquely indicatevarious modes of operation. In FIG. 2A, a current sensor 216 is shownassociated with the control signals exchanged between the thermostat 208and the control board 112. The current is received by the air handlermonitor module 200.

In some HVAC systems, the difference in current between two differentmodes may not be distinguishable with sufficient accuracy. For thesesituations, additional sensing may be required. For example, a sensormay be connected to a specific control line to provide additionalinformation so that the mode of operation can be disambiguated.

Multi-Tap Selection

In FIG. 4, a power supply 404 receives the line power that is eventuallyused to power the motor. The power supply 404 converts the line powerinto power for driving relays, light-emitting diodes (LEDs), and adriver circuit 408. For example, the power supply 404 may include arectifier and a voltage regulator that produce a DC power supply.

In this example, five taps and five control lines are described, thoughgreater or fewer may be implemented. The motor tap connections arelabelled as Tap 1, Tap 2, Tap 3, Tap 4, and Tap 5. FIG. 4 is a retrofitexample in which there are original control lines from the preexistingcontrol board. The original control lines are labeled as OCL 1, OCL 2,OCL 3, OCL 4, and OCL 5.

A first relay 412 connects and disconnects the input power from a binarytree 416 of relays. While use of a binary tree is not necessary, it mayallow for using a fewer number of relays. In the example of FIG. 4,where there are more than four (2²) taps but no more than eight (2³)taps, a three-deep binary tree is used. The binary tree 416 includes afirst level relay 420, a second level relay 424-1, and third levelrelays 428-1 and 428-2.

The binary tree 416 thereby connects the relay 412 to one of the fivetaps. The relay 412 may be oversized or otherwise designed to be lesssensitive to voltage and current transients and may therefore bedisconnected before changing the state of the binary tree 416. By makingthe relay 412 more robust and using it to disconnect power from therelays in the binary tree 416, the relays in the binary tree 416 can besmaller and/or less expensive without sacrificing their longevity.

A set of final connection relays 432-1, 432-2, 432-3, 432-4, and 432-5(collectively, relays 432) connect the motor taps to either the originalset of control lines or respective lines of either the binary tree 416.The relay 432 s may be controlled together according to a single controlsignal.

The relays 432 may be configured such that, in the absence of power, aspring or other mechanism returns the relay 432 s to a state thatconnects the motor taps to the original control lines. In this way, ifthere is a fault in the new motor control circuitry, the motor will beconnected to the original control lines, preserving as much motorfunctionality as possible.

The driver circuit 408 receives power from the power supply and drives anumber of outputs based on a corresponding number of inputs. In theexample of FIG. 4, the driver circuit 408 receives six input signals(not shown individually) and drives six output signals. Each driver maybe a single transistor or, in another implementation, may be aDarlington pair with a flyback diode. In various implementations, thedriver circuit 408 may be implemented by an eight-input, eight-outputintegrated circuit with two of the inputs and outputs unused.

In some implementations, a microcontroller may be implemented thatreceives a digital signal (such as over a serial bus) indicating whichtap to select, and generates individual output signals accordingly. Thedriver circuit 408 may or may not be used, depending on the currentdrive capability of the microcontroller.

A light emitting diode (LED) 436 is powered directly by the power supply404 and therefore indicates whether the power supply 404 is generatingDC power. A resistor 440 allows for a voltage drop between the powersupply 404 and the diode 436.

An LED 444 is driven by the driver circuit 408 according to one of theinputs. The LED 444 is therefore under the control of the input signalsand can be implemented solidly or with a flashing pattern to indicateoperation or to signal error messages. The remaining resistors of FIG. 4function similarly to the resistor 440—allowing a voltage drop between arespective LED and the power supply 404—and will therefore not bediscussed individually.

The driver circuit 408 also controls a coil 448 corresponding to therelay 412, which connects and disconnects the binary tree 416 from theinput power. Connected in parallel to the coil 448 is an LED 452, whichtherefore lights up to indicate that the coil 448 is being driven. Theremaining LEDs in FIG. 4 will not be individually discussed because theyoperate similarly to the LED 452, indicating when a corresponding coilis being energized.

The relays of the binary tree 416 are controlled by coils 456, 460, and464. As an example, the coil 456 controls the relay 420, the coil 460controls the relay 424, and the coil 464 controls the relay 428-1 and428-2. If one additional tap were present, a relay 424-2 may be added,which may be controlled by the same coil 460 that controls the relay424-1. Adding additional taps can then be accomplished by addingadditional relays 428 s, which may all be controlled by the coil 464. Interms of nomenclature, the relay 424-1 in FIG. 4 is a single-poledouble-throw switch, while the relays 428-1 and 428-2 together are adouble-pole double-throw switch.

Coils 468-1, 468-2, and 468-3 (collectively, coils 468) are controlledtogether and operate the relays 432. Although there are five relays 432,the coils 468 may be double-pole double-throw switches, allowing up tosix relays to be controlled by the three coils 468.

In FIG. 5, another example circuit is shown for selectively energizingmotor taps. FIG. 5 includes elements similar to those of FIG. 4 and islimited to four taps. As a result of the fewer number of taps, certaincomponents of FIG. 4 can be eliminated.

In FIG. 6, a functional block diagram of motor hardware includes themotor control circuitry 202 and the circulator blower 108. Thecirculator blower 108 includes a motor 504 that drives a fan 508. Forexample only, the fan may include blades directly affixed to a rotatingshaft of the motor 504. For certain types of motors, such as permanentsplit capacitor (PSC) motors, speed of the motor can be controlled byapplying power to a different one of multiple taps.

For example, the motor 504 is shown with three taps (tap 1, tap 2, andtap 3) and a common terminal. Applying power between tap 1 and thecommon terminal will operate the motor 504 at a first speed, applyingpower between tap 2 and the common terminal will operate the motor 504at a second speed, and applying power between tap 3 and the commonterminal will operate the motor 504 at a third speed. This patternremains the same for motors that have more or fewer taps, such as 4-tapmotors, 5-tap motors, etc.

Generally, the speeds that the motor can run at will increase ordecrease from a first tap to a last tap. However, the taps of motors areoften connected incorrectly when a system is installed or serviced.Therefore, taps 1-3 of the motor 504 may not necessarily correspond toan increasing set of three speeds. Because the motor control circuitry202 may not know which tap corresponds to which speed, the speeds of themotor 504 corresponding to the different taps can be determinedempirically, as described in more detail below.

In a simple implementation of the motor control circuitry 202, aninterface 520 receives a tap selection input, such as from the airhandler monitor module 200 of FIG. 2A. The interface 520 energizes (or,activates) at most one of a set of relays 524-1, 524-2, . . . and 524-n(collectively, relays 524). A simple implementation of the interface 520is therefore a demultiplexer or decoder circuit.

In various implementations, the motor control circuitry 202 may beconfigured to support more than three taps, so that the motor controlcircuitry 202 can be used with a larger variety of motors. In suchcases, additional relays (not shown) may be included and controlled bythe interface 520. For example only, n=5 may be chosen to allow supportfor motors having up to 5 taps.

Based on the tap selection signal, the interface 520 can energize therelay 524-1 to connect a first lead of the incoming AC power to tap 1 ofthe motor 504. Similarly, activating the relay 524-2 provides AC powerto tap 2 of the motor 504. Further, activating the relay 524-n providesAC power to tap n of the motor 504. As shown in FIG. 6, a second lead ofthe incoming AC power is directly connected to the common terminal ofthe motor 504.

For example only, the tap selection signal may assume values of 1, 2, 3,. . . , each value indicating an instruction to activate a correspondingone of the relays 524. Meanwhile, another value, such as 0, indicatesthat all of the relays 524 should be deactivated, de-energizing themotor 504. The control board 112 may generate a signal indicating thatthe motor 504 should be de-energized.

In various implementations, the motor control circuitry 202 may be usedin a retrofit environment, where the control board 112, present in theair handler unit 136 since manufacture, had previously controlled thetaps of the motor 504. The control board 112 may have de-energized thecirculator blower 108 in response to a variety of conditions. Forexample, when a start-up sequence of the air handler unit 136 appears tohave failed for some reason, the control board 112 may attempt todisable the circulator blower 108. As one example, the control board 112may deactivate the circulator blower 108 when a pressure decrease is notidentified after the inducer blower 132 is activated.

In a retrofit environment, the control board 112 may have individuallycontrolled the taps of the motor 504. After installation of the motorcontrol circuitry 202, the control board 112 may still be energizingpins or leads that were previously connected to the taps of the motor504. However, these signals may be ignored in favor of the tap selectionsignal from the air handler monitor module 200.

In other implementations, the tap control signals from the control board112 may collectively act as the disable signal. For example, when all ofthe tap control signals from the control board 112 are deactivated, thisindicates that the control board 112 does not want the circulator blower108 to be operating. Therefore, this lack of control signal activationmay be interpreted by the interface 520 as a disable signal.

Meanwhile, when the control board 112 indicates that one of the tapsshould be activated, the present disclosure may ignore which particulartap is chosen, recognizing that the control board 112 has limitedunderstanding of the taps of the motor 504 and limited information aboutthe operating parameters of the overall HVAC system. In other words,when the control board 112 attempts to activate any tap, the actual tapis chosen by the air handler monitor module 200 irrespective of whichtap is selected by the control board 112.

In some implementations, such as are discussed above with respect toFIGS. 4 and 5, the motor control circuitry 202 may connect the originalcontrol signals to the taps of the motor 504 if the motor controlcircuitry 202 is de-energized or if the motor control circuitry 202experiences a failure.

In FIG. 7A, a high-level example schematic of a 3-tap permanent splitcapacitor (PSC) motor 600 is shown. The 3-tap PSC motor 600 includes afirst winding 604 connected in between a first tap and a commonterminal. A second winding 608 is connected between the first tap and arun capacitor 612. The run capacitor 612 is connected in between thesecond winding 608 and the common terminal. In between the first tap andthe third tap, an autotransformer section 616 is present. At an internaltap of the autotransformer section 616, a second tap is connected.Applying power between the common terminal and one of the 3 taps causesa shaft 620 to rotate.

In FIG. 7B, an example implementation of a 3-tap electronicallycommutated motor (ECM) 650 is shown. An ECM generally does not rely onmultiple taps for speed control. Instead, control circuitry applieswaveforms, such as pulse-width modulated (PWM) signals, to windings of amotor. However, in some situations, such as for repair or retrofitinstallation, a standard ECM (including its speed controller) 654 may bepackaged as the 3-tap ECM 650 to appear electrically analogous to the3-tap PSC motor 600 of FIG. 7A.

For example, the 3 taps may be connected together to provide power tothe standard ECM 654. Meanwhile, a speed controller 658 monitors whichof the taps is actually energized and sends a corresponding speedcommand to the standard ECM 654. The standard ECM 654 then varies thePWM signals to drive the motor at the commanded speed. Energization ofthe taps may be sensed using current sensors 662-1, 662-2, and 662-3,corresponding respectively to the first, second, and third taps. Thespeed controller 658 may be configured to request speeds from thestandard ECM 654 that correspond to the same speeds that would beachieved by the respective taps on the 3-tap PSC motor 600.

While 3-tap motors are depicted in FIG. 7A and FIG. 7B, other numbers oftaps may be used or supported. For example, 2-tap motors, 4-tap motors,and 5-tap motors are also widely available.

In FIGS. 8A-8B, a flowchart of overall fan control operation aftercommissioning of the system is shown. In FIG. 8A, control begins at 704when any call from the thermostat is recognized. At 704, controlbranches depending on the mode of the received call. If the call is forheat, control transfers to 708; if the call is for fan only, controltransfers to 712; and if the call is for cool, control transfers to 716(FIG. 8B).

At 708, control identifies the speed at which to run the motor duringheating. This may be determined by a speed map 720, which may be storedlocally and may be updated from a remote server. The speed map 720identifies what speed the fan should run at for each mode. The speed map720 may also have a mapping from speeds to physical taps on the motor.After identifying the heat speed at 708, control continues at 724.

At 712, control identifies the speed to run the motor at when fan onlyis selected. This is simply an issue of air movement and filtration, asthere is no heating or cooling that may dictate how much airflow isnecessary. Therefore, this fan only speed may be set up by an installeror other HVAC specialist and may be controlled by a user. Controlcontinues at 724.

At 724, the fan is run at the identified speed. At 728, controldetermines whether the call is still present. If so, control remains at724; otherwise, control continues at 732. At 732, the fan is switchedoff by energizing none of the taps of the motor. Control then ends andwaits until the next thermostat call is recognized.

In FIG. 8B, at 716, control runs the fan at the first (lowest) speed inthe speed map 720. When a cooling cycle is first beginning, circulatingair passed through the evaporator at a slower rate will allow theevaporator coil to get down to operating temperature more quickly and totherefore reach peak efficiency more rapidly. As the evaporator coilmoves toward the desired operating temperature, the fan speed can beincreased. The final speed may be selected based on, for example,humidity because slower airflow across the evaporator removes moremoisture from the air.

Control continues at 736, where if the call for cool is still present,control continues at 740; otherwise, control transfers to 744. At 740,control determines whether a time period for the present fan speed haselapsed. If so, control transfers to 748; otherwise, control returns to736. Time periods are determined from a timings file 752, which may beretrieved from or updated by a remote system (which may be referred towith the shorthand “cloud”). All control data from the cloud, includingthe timings file 752, may be pre-programmed, such as from themanufacturer. Using the pre-programmed data, multi-speed operation canbe performed even before network connectivity is available (or insituations where network connectivity never becomes available).

As a cooling cycle begins, the motor is cycled from the slowest speed tothe desired speed, holding each speed for a predetermined period oftime. Therefore, when the time is up at 740, control at 748 switches thefan to run at the next speed in the map.

In some implementations, or with some timing files, some speeds may beskipped. This may be indicated in the timings file 752 by setting thetime for a certain fan speed to be zero. Further, the speed selected in716 does not necessarily have to be the slowest speed: instead, a higherspeed may be selected. For example, if a cooling cycle had been recentlycompleted, times for each speed may be shortened, and the first speedmay be skipped altogether.

Control continues at 754, where if the new speed is the target speed atwhich the fan should run for the duration of the cooling cycle, controlcontinues at 756. Otherwise, control returns to 736, where the presentspeed will be held for a respective period of time. At 756, controlholds the fan at the target speed until the end of the call for cool.

Once the call for cool is no longer present, control transfers to 744.At 744, control switches to a predetermined post-cooling speed in thespeed map 720. For example, the post-cooling speed may be the nextslower speed from the target speed. Control continues at 760, where thepost-cooling speed is held for a predetermined time, which may beestablished by the timings file 752. Once that time has lapsed, controlcontinues at 732 in FIG. 8A.

In FIG. 9A, an alternative implementation for handling a call for coolis shown. The flowchart of FIG. 9A can be compared to that of FIG. 8B.For consistency with FIG. 8B, control arrives from FIG. 8A at 716 inFIG. 9A, where the fan is run at the first (slowest) speed in the map.Control continues at 804, where if the call for cool is still present,control transfers to 808; otherwise, control transfers to 812.

At 808, control evaluates whether the conditions are met to move to thenext fan speed. For example only, this determination may be made asshown in FIG. 9B. At 816, if the conditions are met to move to the nextspeed, control transfers to 820; otherwise, control returns to 804. At820, control switches to the next faster speed in the map. Controlcontinues at 824, where if the target speed has been reached, controltransfers to 828; otherwise, control returns to 804. The target speed isthe speed at which the fan should be run while the cooling system is insteady state to maximize efficiency and comfort (including humiditycontrol).

At 828, control determines whether the call for cool is still present.If so, control remains at 828. Once the call for cool is no longerpresent, control continues at 812. At 812, control switches to apredetermined post-cooling speed. For example, the post-cooling speedmay be one speed slower than the normal cooling fan speed. Controlcontinues at 832, where a timer is evaluated. The timer times how longthe fan has been running in the post-cooling mode. Once thepredetermined time limit is met, control returns to 732 of FIG. 8A. Ifthe time limit has not yet been met, control transfers to 836.

A predetermined temperature split may be defined, where a temperaturesplit is the difference between the temperature of return air arrivingat the evaporator and supply air leaving the evaporator. If thispredetermined split has been met, control also returns to FIG. 8A;otherwise, control continues at 832. In other words, the conditions in832 and 836 are both sufficient, and meeting either will allow the fanto be turned off. In other implementations, both conditions arenecessary, in which case the fan will shut off only once both conditionsare met.

In FIG. 9B, the evaluate operation 808 of FIG. 9A begins at 904. At 904,a split temperature is calculated from a measured supply air temperatureand a measured return air temperature. The split temperature iscalculated by subtracting the two temperatures. At 908, control comparesthe calculated split temperature to a temperature profile, which may bea relationship of desired split temperature vs time. The reference pointfor the time scale may be the time at which the current call for coolarrived.

If the split temperature is greater than the profile, control transfersto 912; otherwise, control transfers to 916. At 912, control integratesthe amount of time (which may be in seconds) that the split temperaturehas been greater than the predefined temperature profile multiplied by again factor. The gain factor may be a constant, and may be equal to one,or may be greater than or less than one. For example, the integrationmay be performed simply by adding the product of time and gain to theprior sum to arrive at the next sum. Control continues at 920, where thesum of the integrating is saved in an accumulator register. Theaccumulator register may be a hardware register of a processor or amemory location; the value in the accumulator register may initially bewritten to a hardware register and then stored to the memory location.

At 924, control determines whether a humidity control mode has beenenabled. If so, control transfers to 928; otherwise, control transfersto 932. At 928, control calculates humidity error by subtracting ameasured humidity from a humidity set point. At 936, control determineswhether this humidity error is above a threshold. If so, this isconsidered a high humidity condition and control transfers to 940;otherwise, control returns to 932.

At 940, control extends the allowed high split temperature by increasingvalues of the temperature profile used in 908. Additionally oralternatively, at 944, control extends the allowed time a lower speedsby increasing the present maximum time limit as used in 916. At 932,control determines whether the sum from 920 is greater than apredetermined limit. If so, control transfers to 948; otherwise, controltransfers to 916. The predetermined limit may be fixed, or may varybased on which speed the motor is running at.

At 948, the split temperature has been greater than the temperatureprofile for a long enough time that a flag is set indicating theconditions are met to move to the next speed. Control then returns, suchas to 816 of FIG. 9A. At 916, control determines whether the time spentat the present speed is greater than a maximum time limit. If so,control transfers to 948; otherwise, control returns without indicatingthat the conditions are met to move to the next speed. In other words,the conditions of 932 and 916 are each sufficient to allow the next fanspeed to be selected. The maximum time limit may be fixed, or may varybased on which speed the motor is running at.

By making the condition at 932 harder to achieve, the adjustment at 940means that more time may be spent at the current speed. Similarly, bymaking the time limit of 916 longer, the adjustment at 944 increases theamount of time that the fan can run at the present speed. The presentspeed is lower than the next speed and low fan speeds cause morehumidity to be extracted from air passing over the evaporator.Therefore, in high humidity situations, the system at 940 and 944increases the amount of time spent at lower speeds do correct for thehumidity error.

In FIG. 10, an example flowchart example implementation of determiningwhich physical fan tap corresponds to which fan speed is shown. Forexample, control may begin at each boot-up cycle. At 1004, controldetermines whether the entire map has already been set. If so, controlends; otherwise, control continues at 1008. At 1008, control selects thefirst physical motor tap for evaluation.

At 1012, control determines whether calls other than a fan only call arepresent. If so, control transfers to 1016 to service the present callregardless of which tap is selected for evaluation; otherwise, controltransfers to 1020. At 1016, control identifies a motor tap to servicethe present call, such as a call for heat or a call for cool. Controlthen runs the fan with the identified tap. Until the map of hardwaretaps to fan speeds is completed, control may assume that the fan tapsare correctly connected in increasing speed order. Then, predeterminedspeed selections for a call for heat or a call for cool may be servicedby the tap expected to correspond to those speeds.

At 1024, control determines whether measurements have already beenperformed on the identified tap. If so, control transfers to 1012;otherwise, control transfers to 1028. At 1028, control measures fancurrent. This measurement may be an aggregate current of multipledevices within the air handler unit 136 (see FIG. 2A). However, evenwith these other contributions to total current, the total current maystill be indicative of the fan current.

At 1032, control stores the measured current in an entry for theidentified tap in a table. These currents will be used to identifyspeeds based on the property that higher speeds require greatercurrents. Therefore, the taps can be sorted in order of increasingcurrent which will therefore correspond to a sort by increasing speed.Control then returns to 1012.

At 1020, control determines whether the evaluation tap has already beenmeasured. If so, control transfers to 1036; otherwise, control transfersto 1040. At 1040, the evaluation tap has not yet been measured andtherefore control runs the fan using the evaluation tap. At 1044,control measures the fan current and at 1048 control creates an entry inthe table for the evaluation tap and stores the measured current.Control then continues at 1036.

At 1036, control determines whether there are any additional connectedtaps that have not yet been measured. If so, control transfers to 1052;otherwise, control transfers to 1056. At 1052, control selects the nextconnected tap that has not been measured as the evaluation tap. Controlthen returns to 1012. At 1056, all of the connected motor taps have beenmeasured and therefore the fan speed map is set by sorting the table bycurrent. Sorting may be performed by any suitable process, includingbubble sort, insertion sort, or quicksort. In fact, as each currentvalue is measured, a new entry in the fan speed map may be inserted inthe correct sorted position, such that the map is already sorted whenthe last current value is added.

The sorted table then indicates, in increasing order (equivalently, inother implementations, decreasing order) the motor taps corresponding toincreasing speeds. The speeds in the table may be absolute speeds, asmeasured in revolutions per minute (rpm). However, in otherimplementations, the speeds may simply be comparative, with noinformation other than that speed 2 is faster than speed 1, speed 3 isfaster than speed 2, etc. Control then ends.

In FIG. 11, a plot of split temperature versus time is shown, withtemperature split in degrees Fahrenheit shown on the Y axis and timefrom compressor startup in seconds shown on the X axis. Bars at −17° F.and −22° F. indicate an envelope within which the split temperatureshould be located during efficient steady-state operation of a coolingsystem. Note that the split temperature entered this envelope atapproximately 450 seconds.

The measured temperature split from a compressor run is shown by trace1100. When a best fit line 1104 is calculated for a startup region ofthe temperature split 1100 (such as between 60 seconds and 120 seconds),the best fit line 1104 can be extrapolated to hit the bottom of thetemperature split envelope. This intercept point is labeled as 1108 andthe time associated with this intercept may be used in determining whento transition the fan from one speed to the next.

By running the fan at slower speeds for a longer period of time, thetemperature split can reach the goal range more quickly. In fact,overachieving with a greater split (below the envelope in FIG. 11)temporarily may be helpful for driving dehumidification early in thecompressor run. The temperature split of the compressor system can thenbe returned to the envelope by increasing the fan speed.

In FIG. 12, the fan speed is managed to speed the arrival of the splittemperature into the envelope. Note that the split temperature entersthe envelope in FIG. 12 at approximately 230 seconds. By “managed,” thepresent disclosure means that the fan speed is controlled, such as isshown in FIG. 13. By starting the fan off at a slower speed that is heldfor a longer time, the split temperature can arrive at the steady-stateenvelope more rapidly.

FIG. 13 depicts the managed fan speed that results in the splittemperature of FIG. 12. The speed is expressed as a percentage of totalspeed. The four step changes between 60% and 100% correspond to the fourtransitions between five motor speeds. The transitions may be performedbased on times determined according to the following process.

Time Determination

For the first compressor run (and until network connectivity isestablished), the local air handler control module includes a predefinedset of transition times determining when to transition from one motorspeed to the next. For example, the predefined transition times may beprogrammed during manufacturing or may be input as part of commissioningthe monitoring system.

After each run of the compressor, data is uploaded to the remote system(or, “cloud”) for analysis. The cloud analyzes the data from thecompressor run and updates one or more of the transition times. Theupdated transition times are fed back to the compressor system for usein subsequent compressor runs. The remote system may zero in on onetransition at a time. For example, a compressor with five operatingspeeds allows for four transitions. The first transition (from theslowest speed to the second-slowest speed) may be determined first, thesecond transition may be determined second, etc. The final transitiondetermined is then the transition from the second-fastest compressorspeed to the fastest compressor speed. In various implementations, asthe first transition time is being determined, the subsequent transitiontimes are being updated.

In FIG. 14A and FIG. 14B, a process is shown for determining thespecific times to transition the circulator blower (also referred tohere as the fan) from one speed to the next. For example, these timesmay be used by a process such as shown in FIGS. 8A-8B to determine whento transition from one speed to the next. In other words, the processdescribed in FIG. 14A and FIG. 14B may generate the timings file 752shown in FIG. 8B. The local HVAC system, and more particularly the airhandler monitor module 200 of FIG. 2A, may be pre-programmed withcontrol data, including the timings file 752. The process of FIG. 14Aand FIG. 14B is then used to update the timings file 752.

Control begins in FIG. 14A when compressor run data is received. Thecompressor run data may be received after conclusion of a compressorrun—that is, once the compressor has turned off In some implementations,the compressor run data may be received while the compressor is stillrunning. For example, after a predetermined length of time, theremaining compressor run data may not be helpful in establishing speedtransitions. Therefore, after a predetermined period of time (such astwenty minutes), the gathered data may be provided as a compressor run.

Upon receipt of compressor run data, control begins at 1204, wherecontrol determines whether a time established flag for each of thepotential speed transitions has been set. If all the time establishedflags have been set, control transfers to 1208; otherwise, controltransfers to 1212. The number of transitions depends on the number ofspeeds of the motor. For example, a process such as is disclosed in FIG.10 may be used to determine how many speeds the blower motor can operateat. In commonly-available systems, the number of speeds varies from 2 to5.

The number of transitions is one fewer than the number of speeds. Forexample, a five-speed motor requires four transitions. In someimplementations, some speeds may be skipped depending upon operatingconditions, in which case there may be fewer transitions. In otheroperating circumstances and configurations, the fan may never need totransition to the highest speed. In such cases, the number of actualtransitions will be fewer than the number of possible transitions.

The time established flags referred to in 1204 indicate whether aspecific transition time has been established for one of the potentialtransitions. As a time is established for each potential transition, thecorresponding time established flag is set. The transition times may beset in chronological order, establishing a time for a first transition(from the lower speed to next lower speed) before moving on to establishthe transition time for the second transition (that is from thesecond-slowest speed to the third-slowest speed).

At 1208, all of the time established flags are set, indicating that nofurther transition time adjustments are needed. However, if changes tothe HVAC system are detected at 1208, control transfers to 1216.Otherwise, control ends. Changes to the HVAC system may includereplenishment of refrigerant, adjusting of ductwork or registers, or anyother service or configuration changes. These changes may be reported bya contractor or homeowner, or may be detected from other measuredvariables. At 1216, control clears the time established flags for alltransitions so that new transitions times can be established based onpotential new operating conditions of the HVAC system. Control thancontinues at 1220.

At 1212, control determines whether a first run flag is set. If so,control transfer to 1224; otherwise, control transfers to 1220. Thefirst run flag determines whether the first run of the compressor hasbeen evaluated. Once the first run of the compressor has been evaluated,the first run flag is set and the initial evaluation is not repeated.

At 1220, the first run flag has not been set or something has changed inthe HVAC system and therefore initial analysis is done. Controlcalculates a best fit line for the temperature split data within acertain window of time. This window of time may be referred to as astartup window and in one example may be from 60 to 120 seconds. Thezero reference may be the time at which the compressor begins to run.

At 1228, control extrapolates the best fit line to intercept the lowerbound of a predefined temperature split envelope. This intercept time isthan used for future calculations. The temperature split envelope may befrom −16° F. to −22° F., where the lower bound refers to the mostnegative number, not the lowest absolute value. That means that the bestfit line is extrapolated to, in this example, −22° F.

At 1232, control calculates initial times for all of the transitionsbased on the sum of the intercept time and respective offsets from a setof offsets. In other words, the initial time for the first transition isequal to the intercept time plus a first offset from the set of offsets,the second transition time is initialized to the sum of the intercepttime plus the second offset from the set, etc. In one example for a5-speed, 4-transition fan, the offsets may be zero seconds, 200 seconds,300 seconds, and 500 seconds. Control continues at 1236, where controlsets the first run flag to indicate that processing of the firstcompressor run is complete. Control then continues at 1224.

At 1224, control selects the first potential transition (that is, fromthe lowest speed to the next-lowest speed). Control continues at 1240,where control determines whether the time established flag for theselected transition has been set. If so, control transfers to 1244;otherwise, control transfers to 1248 of FIG. 14B. At 1244, controlselects the next transition and returns to 1240.

At 1248 of FIG. 14B, control extracts run data for a time windowestablished by the transition time for the selected transition and awindow width. The window width may be a predetermined number, such as 50seconds. The window width may be adjusted based on the number oftransitions, and may vary per transition. In other words, the windowwidth may increase (or decrease) for each subsequent transition. Thetime for the selected transition may determine a beginning of thewindow, an end of the window, or middle of the window.

Control continues at 1252, where control identifies the minimumtemperature split value from within the extracted time window. At 1256,control determines whether the minimum temperature split value is withina temperature split band. If so, control transfers to 1260; otherwise,control transfer to 1264. The temperature split band may vary based onthe number of transitions. For a given number of transitions, thetemperature split band may be specified separately for each transition.In one example, the temperature split band is from −22° F. to −23.5° F.

At 1260, because the minimum temperature split value is within thedesired band, control leaves the transition time for the selectedtransition as is and sets the time established flag for the selectedtransition. Control then ends. At 1264, the temperature split did notreach the temperature split band and therefore the time for the selectedtransition is increased. The amount of increase is determined by aproduct of a gain factor and a temperature difference. Temperaturedifference is between the minimum temperature split value and a highside of the temperature split band. The gain may vary based on thenumber of the transitions for the system and may also vary for eachtransition.

Control continues at 1266, where if the increased transition time hasnot exceeded a predetermined limit, control transfers to 1268; if theincreased time has exceeded the predetermined limit, control transfersto 1270. At 1268, if there are subsequent transitions, control transfersto 1272; otherwise, controls transfers to 1276. For example, if the timefor a second transition has been increased, and there are third andfourth transitions because the motor is a 5 speed motor, control willtransfer to 1272. At 1272, control selects the next transition andreturns to 1264.

At 1270, control reduces the transition time back down to thepredetermined limit and sets the time established flag for the selectedtransition. Control then continues at 1276. However, in otherimplementations, control may proceed from 1270 to 1268 to potentiallyincrease subsequent transition times. At 1276, control sends the updatedtransition times to the HVAC system for use in future compressor runs.Control then ends.

Additional Features

If the circulator blower motor does not appear to be running—forexample, the power consumption of the motor is close to zero—while oneof the motor taps is connected to power, this may be an indication of afailure of the motor. For example only, part of the motor winding mayhave an open circuit. To address this problem, the control system mayiterate through the other available taps to see if the motor will rotatewhen any other tap is connected.

The tap used for heating, and the target tap used for cooling, may bedynamically adjusted based on observed operation of the HVAC system. Forexample, if measured or inferred airflow is too low, the speed may beincreased by selecting the next motor tap. Similarly, excessive airflow(which may result in, during cooling, increased humidity) may becountered by selecting a motor tap for a lower speed.

Some problems with HVAC systems, such as refrigerant undercharge orovercharge, can be ameliorated by adjusting fan speed. For example, in arefrigerant undercharge situation, the fan speed may be reduced.

Conclusion

The foregoing description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Thebroad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. It should be understood thatone or more steps within a method may be executed in different order (orconcurrently) without altering the principles of the present disclosure.Further, although each of the embodiments is described above as havingcertain features, any one or more of those features described withrespect to any embodiment of the disclosure can be implemented in and/orcombined with features of any of the other embodiments, even if thatcombination is not explicitly described. In other words, the describedembodiments are not mutually exclusive, and permutations of one or moreembodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example,between modules, circuit elements, semiconductor layers, etc.) aredescribed using various terms, including “connected,” “engaged,”“coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and“disposed.” Unless explicitly described as being “direct,” when arelationship between first and second elements is described in the abovedisclosure, that relationship can be a direct relationship where noother intervening elements are present between the first and secondelements, but can also be an indirect relationship where one or moreintervening elements are present (either spatially or functionally)between the first and second elements. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A OR BOR C), using a non-exclusive logical OR, and should not be construed tomean “at least one of A, at least one of B, and at least one of C.”

In the figures, the direction of an arrow, as indicated by thearrowhead, generally demonstrates the flow of information (such as dataor instructions) that is of interest to the illustration. For example,when element A and element B exchange a variety of information butinformation transmitted from element A to element B is relevant to theillustration, the arrow may point from element A to element B. Thisunidirectional arrow does not imply that no other information istransmitted from element B to element A. Further, for information sentfrom element A to element B, element B may send requests for, or receiptacknowledgements of, the information to element A.

In this application, including the definitions below, the term “module”or the term “controller” may be replaced with the term “circuit.” Theterm “module” may refer to, be part of, or include: an ApplicationSpecific Integrated Circuit (ASIC); a digital, analog, or mixedanalog/digital discrete circuit; a digital, analog, or mixedanalog/digital integrated circuit; a combinational logic circuit; afield programmable gate array (FPGA); a processor circuit (shared,dedicated, or group) that executes code; a memory circuit (shared,dedicated, or group) that stores code executed by the processor circuit;other suitable hardware components that provide the describedfunctionality; or a combination of some or all of the above, such as ina system-on-chip.

The module may include one or more interface circuits. In some examples,the interface circuits may include wired or wireless interfaces that areconnected to a local area network (LAN), the Internet, a wide areanetwork (WAN), or combinations thereof. The functionality of any givenmodule of the present disclosure may be distributed among multiplemodules that are connected via interface circuits. For example, multiplemodules may allow load balancing. In a further example, a server (alsoknown as remote, or cloud) module may accomplish some functionality onbehalf of a client module.

Some or all hardware features of a module may be defined using alanguage for hardware description, such as IEEE Standard 1364-2005(commonly called “Verilog”) and IEEE Standard 1076-2008 (commonly called“VHDL”). The hardware description language may be used to manufactureand/or program a hardware circuit. In some implementations, some or allfeatures of a module may be defined by a language, such as IEEE1666-2005 (commonly called “SystemC”), that encompasses both code, asdescribed below, and hardware description.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes, datastructures, and/or objects. The term shared processor circuitencompasses a single processor circuit that executes some or all codefrom multiple modules. The term group processor circuit encompasses aprocessor circuit that, in combination with additional processorcircuits, executes some or all code from one or more modules. Referencesto multiple processor circuits encompass multiple processor circuits ondiscrete dies, multiple processor circuits on a single die, multiplecores of a single processor circuit, multiple threads of a singleprocessor circuit, or a combination of the above. The term shared memorycircuit encompasses a single memory circuit that stores some or all codefrom multiple modules. The term group memory circuit encompasses amemory circuit that, in combination with additional memories, storessome or all code from one or more modules.

The term memory circuit is a subset of the term computer-readablemedium. The term computer-readable medium, as used herein, does notencompass transitory electrical or electromagnetic signals propagatingthrough a medium (such as on a carrier wave); the term computer-readablemedium may therefore be considered tangible and non-transitory.Non-limiting examples of a non-transitory computer-readable medium arenonvolatile memory circuits (such as a flash memory circuit, an erasableprogrammable read-only memory circuit, or a mask read-only memorycircuit), volatile memory circuits (such as a static random accessmemory circuit or a dynamic random access memory circuit), magneticstorage media (such as an analog or digital magnetic tape or a hard diskdrive), and optical storage media (such as a CD, a DVD, or a Blu-rayDisc).

The apparatuses and methods described in this application may bepartially or fully implemented by a special purpose computer created byconfiguring a general purpose computer to execute one or more particularfunctions embodied in computer programs. The functional blocks andflowchart elements described above serve as software specifications,which can be translated into the computer programs by the routine workof a skilled technician or programmer.

The computer programs include processor-executable instructions that arestored on at least one non-transitory computer-readable medium. Thecomputer programs may also include or rely on stored data. The computerprograms may encompass a basic input/output system (BIOS) that interactswith hardware of the special purpose computer, device drivers thatinteract with particular devices of the special purpose computer, one ormore operating systems, user applications, background services,background applications, etc.

The computer programs may include: (i) descriptive text to be parsed,such as HTML (hypertext markup language), XML (extensible markuplanguage), or JSON (JavaScript Object Notation) (ii) assembly code,(iii) object code generated from source code by a compiler, (iv) sourcecode for execution by an interpreter, (v) source code for compilationand execution by a just-in-time compiler, etc. As examples only, sourcecode may be written using syntax from languages including C, C++, C#,Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl,Pascal, Curl, OCaml, Javascript®, HTML5 (Hypertext Markup Language 5threvision), Ada, ASP (Active Server Pages), PHP (PHP: HypertextPreprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, VisualBasic®, Lua, MATLAB, SIMULINK, and Python®.

None of the elements recited in the claims are intended to be ameans-plus-function element within the meaning of 35 U.S.C. §112(f)unless an element is expressly recited using the phrase “means for,” orin the case of a method claim using the phrases “operation for” or “stepfor.”

What is claimed is:
 1. A circulator blower controller for a circulatorblower of a heating, ventilation, and air conditioning (HVAC) system ofa building, the circulator blower controller comprising: an interfaceconfigured to receive a demand signal from a thermostat, the demandsignal specifying an operating mode for the HVAC system; a switchingcircuit configured to, in response to a tap selection signal,selectively connect power to one of a plurality of taps of a motor ofthe circulator blower; a data store configured to store a mapping from aplurality of speeds to the plurality of taps; and a processor configuredto: for each tap of the plurality of taps, observe power consumed by thecirculator blower while power is connected to the tap by the switchingcircuit; determine the mapping by sorting the taps based on observedpower consumption; select a first speed based on the demand signal fromthe thermostat; identify a first tap from the mapping based on the firstspeed; and in response to identifying the first tap, generate the tapselection signal to control the switching circuit to connect power tothe first tap.
 2. A circulator blower system comprising: the circulatorblower controller of claim 1; and the circulator blower, wherein thecirculator blower includes (i) the motor and (ii) a fan driven by themotor and configured to circulate air within the building.
 3. Thecirculator blower system of claim 2, wherein the motor comprises atleast one of: an electronically commutated motor (ECM) configured suchthat each of the plurality of taps instructs the ECM to run at arespective speed; and a permanent split capacitor (PSC) motor includinga winding and configured such that each of the plurality of tapscorresponds to different points along the winding.
 4. The circulatorblower system of claim 3, wherein the motor comprises: the ECM; aplurality of sensors that determine which of the plurality of taps isactivated; and a speed controller configured to control the ECM torotate at a speed based on which of the plurality of taps is activated.5. The circulator blower controller of claim 1, wherein the operatingmode is selected from a plurality of operating modes that include a coolmode and a fan only mode.
 6. The circulator blower controller of claim5, wherein the processor is configured to, in response to the demandsignal specifying the fan only mode, set the first speed to a speeddefined by a user of the building.
 7. The circulator blower controllerof claim 5, wherein: the plurality of operating modes further includes aheat mode; and the processor is configured to, in response to the demandsignal specifying the heat mode, set the first speed to a speed definedby a user of the building.
 8. The circulator blower controller of claim5, wherein the processor is configured to, in response to the demandsignal specifying the cool mode: select the first speed according to apredetermined initial speed; after a first predetermined period of timefollowing selection of the first speed, select a second speed that isfaster than the first speed; and in response to selection of the secondspeed, (i) identify a second tap from the mapping based on the secondspeed and (ii) generate the tap selection signal to control theswitching circuit to connect power to the second tap.
 9. The circulatorblower controller of claim 8, wherein the predetermined initial speed isa lowest speed of the circulator blower.
 10. The circulator blowercontroller of claim 8, wherein the processor is configured to, inresponse to the demand signal specifying the cool mode: after a secondpredetermined period of time following selection of the second speed,select a third speed that is faster than the second speed; and inresponse to selection of the third speed, (i) identify a third tap fromthe mapping based on the third speed and (ii) generate the tap selectionsignal to control the switching circuit to connect power to the thirdtap.
 11. The circulator blower controller of claim 5, wherein theprocessor is configured to, in response to the demand signal specifyingthe cool mode: select the first speed according to a predeterminedinitial speed; evaluate an operating condition of the HVAC system; inresponse to the operating condition of the HVAC system meeting a firstpredetermined criterion, select a second speed that is faster than thefirst speed; and in response to selection of the second speed, identifya second tap from the mapping based on the second speed and generate thetap selection signal to control the switching circuit to connect powerto the second tap.
 12. The circulator blower controller of claim 11,wherein: the operating condition of the HVAC system is temperaturesplit; the temperature split is based on a difference between supply airleaving an evaporator coil of the HVAC system and return air arriving atthe evaporator coil; the processor is configured to integrate timeperiods during which the temperature split diverged from a predeterminedtemperature profile; and the first predetermined criterion is theintegration exceeding a first threshold.
 13. The circulator blowercontroller of claim 12, wherein the processor is configured to, inresponse to determining that a humidity in a conditioned space of thebuilding exceeds a desired humidity, increase the first threshold. 14.The circulator blower controller of claim 12, wherein the processor isconfigured to perform the integration by, for each time period duringwhich the temperature split diverged from the predetermined temperatureprofile, adding a product of a gain factor and a length of the timeperiod to an accumulator register.
 15. The circulator blower controllerof claim 12, wherein the processor is configured to: in response toselection of the second speed, (i) evaluate the operating condition ofthe HVAC system and (ii) in response to the operating condition of theHVAC system meeting a second predetermined criterion, select a thirdspeed that is faster than the second speed; and in response to selectionof the third speed, (i) identify a third tap from the mapping based onthe third speed and (ii) generate the tap selection signal to controlthe switching circuit to connect power to the third tap, wherein thesecond predetermined criterion is the integration exceeding a secondthreshold.
 16. The circulator blower controller of claim 11, wherein theprocessor is configured to, after a first predetermined period of timefollowing selection of the first speed, select the second speed.
 17. Thecirculator blower controller of claim 16, wherein the processor isconfigured to, in response to determining that a humidity in aconditioned space of the building exceeds a desired humidity, increasethe first predetermined period of time.
 18. The circulator blowercontroller of claim 5, wherein the processor is configured to, inresponse to the demand signal specifying the cool mode: selectivelydetermine a refrigerant undercharge condition of the HVAC system; and inresponse to determining the refrigerant undercharge condition, (i)select a slower speed, (ii) identify a second tap from the mapping basedon the slower speed, and (iii) generate the tap selection signal tocontrol the switching circuit to connect power to the second tap. 19.The circulator blower controller of claim 1, wherein: the processor isconfigured to, until the mapping includes entries for all of theplurality of taps, observe the power consumed; and observing the powerconsumed includes, while no demand signal is received from thethermostat, iterating through taps of the plurality of taps bygenerating the tap selection signal to control the switching circuit toconnect power to an evaluation tap and observing the power consumedwhile power is connected to the evaluation tap.
 20. The circulatorblower controller of claim 1, wherein the processor is configured togenerate the tap selection signal to control the switching circuit toconnect power to a second tap in response to determining that the motoris not operating while power is connected to the first tap.